Carbamates of rapamycin

ABSTRACT

A compound of the structure ##STR1## wherein R 1  and R 2  are each, independently, hydrogen, or --CONH--O--(CR 3  R 4 ) m  Z; 
     R 3  and R 4  are each, independently, hydrogen, alkyl, cycloalkyl, --CF 3 , or F; 
     Z is hydrogen, alkyl, --OR 5 , --SR 5 , --NR 5  R 6 , --CN, --CF 3 , --OAr, --Ar, or R 7  ; 
     R 5  and R 6  are each, independently, hydrogen, alkyl, arylalkyl, alkenyl, alkynyl, alkoxyalkyl, alkylthioalkyl, alkylaminoalkyl, dialkylaminoalkyl, cycloalkyl, or Ar; 
     R 7  is ##STR2## or --C.tbd.C--R 11  ; R 8 , R 9 , R 10 , and R 11  are each, independently, hydrogen, alkyl of 1-6 carbon atoms, halogen, or phenyl, wherein the phenyl group may be optionally mono-, di-, or tri-substituted; 
     Ar is an aryl radical that may be optionally mono-, di-, or tri-substituted; and 
     m=1-6; 
     with the proviso that R 1  and R 2  are both not hydrogen, or a pharmaceutically acceptable salt thereof which is useful as an immunosuppressive, antiinflammatory, antifungal, antiproliferative, and antitumor agent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 08/284,765 filed Aug. 2, 1994 which is a continuation-in-part of Ser. No. 08/160,984, filed Dec. 1, 1993 abandoned, which is a divisional of Ser. No. 08/054,655, filed Apr. 23, 1993 (now U.S. Pat. No. 5,302,584) which is a continuation-in-part of Ser. No. 07/960,597, filed Oct. 13, 1992 abandoned.

BACKGROUND OF THE INVENTION

This invention relates to carbamates of rapamycin and a method for using them for inducing immunosuppression, and in the treatment of transplantation rejection, graft vs. host disease, autoimmune diseases, diseases of inflammation, solid tumors, fungal infections, and hyperproliferative vascular disorders.

Rapamycin is a macrocyclic triene antibiotic produced by Streptomyces hygroscopicus, which was found to have antifungal activity, particularly against Candida albicans, both in vitro and in vivo [C. Vezina et al., J. Antibiot. 28, 721 (1975); S. N. Sehgal et al., J. Antibiot. 28, 727 (1975); H. A. Baker et al., J. Antibiot. 31, 539 (1978); U.S. Pat. No. 3,929,992; and U.S. Pat. No. 3,993,749].

Rapamycin alone (U.S. Pat. No. 4,885,171)or in combination with picibanil (U.S. Pat. No. 4,401,653) has been shown to have antitumor activity. R. Martel et al. [Can. J. Physiol. Pharmacol. 55, 48 (1977)] disclosed that rapamycin is effective in the experimental allergic encephalomyelitis model, a model for multiple sclerosis; in the adjuvant arthritis model, a model for rheumatoid arthritis; and effectively inhibited the formation of IgE-like antibodies.

The immunosuppressive effects of rapamycin have been disclosed in FASEB 3, 3411 (1989). Cyclosporin A and FK-506, other macrocyclic molecules, also have been shown to be effective as immunosuppressive agents, therefore useful in preventing transplant rejection [FASEB 3, 3411 (1989); FASEB 3, 5256 (1989); R. Y. Calne et al., Lancet 1183 (1978); and U.S. Pat. No. 5,100,899].

Rapamycin has also been shown to be useful in preventing or treating systemic lupus erythematosus [U.S. Pat. No. 5,078,999], pulmonary inflammation [U.S. Pat. No. 5,080,899], insulin dependent diabetes mellitus [Fifth Int. Conf. Inflamm. Res. Assoc. 121 (Abstract), (1990)], and smooth muscle cell proliferation and intimal thickening following vascular injury [Morris, R. J. Heart Lung Transplant 11 (pt. 2): 197 (1992)].

Mono- and diacylated derivatives of rapamycin (esterified at the 28 and 43 positions) have been shown to be useful as antifungal agents (U.S. Pat. No. 4,316,885) and used to make water soluble prodrugs of rapamycin (U.S. Pat. No. 4,650,803). Recently, the numbering convention for rapamycin has been changed; therefore according to Chemical Abstracts nomenclature, the esters described above would be at the 31- and 42- positions. U.S. Pat. No. 5,118,678 discloses carbamates of rapamycin that are useful as immunosuppressive, anti-inflammatory, antifungal, and antitumor agents.

DESCRIPTION OF THE INVENTION

This invention provides derivatives of rapamycin which are useful as immunosuppressive, antiinflammatory, antifungal, antiproliferative, and antitumor agents having the structure ##STR3## wherein R¹ and R² are each, independently, hydrogen, --CONH--[(CR³ R⁴)_(m) (--A--(CR⁵ R⁶)_(n))_(p) ]_(q) --B; ##STR4## R³, R⁴, R⁵, R⁶, and B are each, independently, hydrogen, alkyl of 1-6 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthioalkyl of 2-12 carbon atoms, alkylaminoalkyl of 2-12 carbon atoms, dialkylaminoalkyl of 3-12 carbon atoms, arylalkyl of 7-10 carbon atoms, cycloalkyl of 3-8 carbon atoms, --OR⁷, --SR⁷, halogen, --CN, --NO₂, --CF₃, --COR⁷, --CO₂ R⁷, --CONHR⁷, --SO₂ R⁷, --OSO₃ R⁷, --NR⁷ R⁸, --NHCOR⁷, --NHSO₂ R⁷, or Ar;

R⁷ and R⁸ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthioalkyl of 2-12 carbon atoms, alkylaminoalkyl of 2-12 carbon atoms, dialkylaminoalkyl of 3-12 carbon atoms, cycloalkyl of 3-8 carbon atoms, or Ar;

R⁹ and R¹⁰ are each, independently, alkyl of 1-6 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthioalkyl of 2-12 carbon atoms, alkylaminoalkyl of 2-12 carbon atoms, dialkylaminoalkyl of 3-12 carbon atoms, arylalkyl of 7-10 carbon atoms, cycloalkyl of 3-8 carbon atoms, --CF₃, --COR⁷, --CO₂ R⁷, --CONHR⁷, --SO₂ R⁷, or Ar;

A is --CH₂ --, --NR⁷ --, --O--, --S--, --SO--, --SO₂ --, --PR⁷ --, --CO--, --NHCO--, --NHSO--, or --P(O)(R⁷)--;

Ar is phenyl, naphthyl, pyridyl, quinolyl, isoquinolyl, quinoxalyl, thienyl, thionaphthyl, furyl, benzofuryl, benzodioxyl, benzoxazolyl, benzoisoxazolyl, indolyl, thiazolyl, isoxazolyl, pyrimidinyl, pyrazinyl, imidazolyl, benzopyranyl, benz[b]thiophenolyl, benzimidazolyl, benzthiazolyl, benzodioxolyl, piperidinyl, morpholinyl, piperazinyl, tetrahydrofuranyl, or pyrrolidinyl; wherein the Ar group may be optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H; ##STR5## is a nitrogen containing heterocycle that may be saturated, unsaturated, or partially unsaturated, and may be optionally mono-, di-, or tri- substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H;

with the proviso that R¹ and R² are not both hydrogen;

m=0-6;

n=0-6;

p=0-1;

q=0-1;

or a pharmaceutically acceptable salt thereof.

The pharmaceutically acceptable salts are those derived from such inorganic cations such as sodium, potassium, and the like; organic bases such as: mono-, di-, and trialkyl amines of 1-6 carbon atoms, per alkyl group and mono-, di-, and trihydroxyalkyl amines of 1-6 carbon atoms per alkyl group, and the like; and organic and inorganic acids -as: acetic, lactic, citric, tartaric, succinic, maleic, malonic, gluconic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, and similarly known acceptable acids.

It is preferred that the aryl portion of the arylalkyl substituent is a phenyl, piperazinyl, piperidinyl, or pyridyl group that is optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, dialkylamino of 1-6 carbon atoms per alkyl group, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H. The term alkyl includes both straight chain and branched alkyl groups.

It is preferred that ##STR6## is a pyridyl, pyrazinyl, piperidinyl, morpholinyl, piperazinyl, pyrrolidinyl, thiazolyl, pyrimidinyl, isoxazolyl, pyrrolidinyl, or imidazolyl group that may be optionally substituted as described above.

This invention also discloses preferred alkenyl and alkynylamino carbamates having the structure ##STR7## wherein R¹ and R² are each, independently, hydrogen, or --CONH--O--(CR³ R⁴)_(m) Z;

R³ and R⁴ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, cycloalkyl of 3-8 carbon atoms, --CF₃, or F;

Z is hydrogen, alkyl of 1-6 carbon atoms, --OR⁵, --SR⁵, --NR⁵ R⁶, --CN, --CF₃, --OAr, --Ar, or R⁷ ;

R⁵ and R⁶ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, arylalkyl of 4-10 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthioalkyl of 2-12 carbon atoms, alkylaminoalkyl of 2-12 carbon atoms, dialkylaminoalkyl of 3-12 carbon atoms, cycloalkyl of 3-8 carbon atoms, or Ar;

R⁷ is ##STR8## or --C.tbd.C--R¹¹ ; R⁸, R⁹, R¹⁰, and R¹¹ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, halogen, or phenyl, wherein the phenyl group may be optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, trifluoroalkoxy of 2-7 carbon atoms, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H;

Ar is an aryl radical that may be optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, trifluoroalkoxy of 2-7 carbon atoms, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H; and

m=1-6;

with the proviso that R¹ and R² are both not hydrogen, or a pharmaceutically acceptable salt thereof.

For the compounds having structure II (immediately above), the term alkyl of 1-6 carbon atoms, includes both straight chain as well as branched carbon chains. When any of the generic terms (i.e., CR³ R⁴) are contained more than once in a given compound, each may be the same or different. Any chiral center present can have either R or S configuration, depending on the configuration of the starting material used; this disclosure covers both enantiomers. The pharmaceutically acceptable salts of the compounds having structure II are the same as was defined following the compounds of structure I.

It is preferred that the aryl radical of Ar and the aryl moiety of the arylalkyl substituent is a phenyl, naphthyl, pyridyl, quinolinyl, isoquinolinyl, quinoxalyl, thienyl, thionaphthyl, furyl, benzofuryl, benzodioxyl, benzoxazolyl, benzoisoxazolyl, indolyl, thiazolyl, isoxazolyl, pyrimidinyl, pyrazinyl, imidazolyl, benzopyranyl, benz[b]thiophenolyl, benzimidazolyl, benzthiazolyl, benzodioxolyl, piperidinyl, morpholinyl, piperazinyl, tetrahydrofuranyl, or pyrrolidinyl radical that is optionally mono-, di-, or tri- substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, trifluoroalkoxy of 2-7 carbon atoms, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H. It is more preferred that the aryl radical of Ar and the aryl moiety of the arylalkyl substituent is a phenyl, pyridyl, furyl, quinolinyl, isoquinolinyl, piperazinyl, or piperidinyl radical.

Preferred compounds of this invention include those in which R² is hydrogen; those in which R² is hydrogen and m=1-3; and those in which R² is hydrogen, m=1-3, and Z is Ar or R⁷.

The compounds of this invention carbamylated at the 42-position or at both the 31- and 42-positions can be prepared by converting the 42- and/or 31-alcohols of rapamycin to a carbonate (see Example 1) followed by reaction with an appropriately substituted amine to provide the desired carbamate. Alternatively, the compounds of this invention carbamylated at the 42-position or at both the 31- and 42-positions can be prepared by reacting rapamycin with an appropriately substituted isocyanate under neutral conditions or in the presence of a base, such as pyridine. Preparation of carbamates of rapamycin using isocyanate starting materials was disclosed in U.S. Pat. No. 5,118,678, which is hereby incorporated by reference. The compounds of structure II, it is preferred that the carbamates are formed via the carbonate intermediate.

The 31-carbamylated compounds of this invention can be prepared by protecting the 42-alcohol of rapamycin with a protecting group, such as with a tert-butyl dimethylsilyl group, followed by carbamylation of the 31-position by the procedures described above. Removal of the protecting group provides the 31-carbamylated compounds. In the case of the tert-butyl dimethylsilyl protecting group, deprotection can be accomplished under mildly acidic conditions.

Having the 31-position carbamylated and the 42-position deprotected, the 42-position can be carbamylated using a different amine (via the carbonate) or isocyanate than was reacted with the 31-alcohol, to give compounds having different carbamates at the 31- and 42- positions. Alternatively, the 42-carbamylated compounds, prepared as described above, can be reacted with a different amine (via the carbonate) or isocyanate to provide compounds having different carbamates at the 31- and 42-positions.

The amines and isocyanates used to prepare the compounds of the invention are commercially available or can be prepared by methods that are disclosed in the literature.

This invention also covers analogous carbamates of other rapamycins such as, but not limited to, 29-demethoxyrapamycin, [U.S. Pat. No. 4,375,464, 32-demethoxyrapamycin under C.A. nomenclature]; rapamycin derivatives in which the double bonds in the 1-, 3-, and/or 5-positions have been reduced [U.S. Pat. No. 5,023,262]; 42-oxorapamycin [U.S. Pat. No. 5,023,262]; 29-desmethylrapamycin [U.S. Pat. No. 5,093,339, 32-desmethylrapamycin under C.A. nomenclature]; 7,29-bisdesmethylrapamycin [U.S. Pat. No. 5,093,338, 7,32-desmethylrapamycin under C.A. nomenclature]; and 15-hydroxy- and 15,27-bishydroxy- rapamycin [U.S. Pat. No. 5,102,876]. The disclosures in the above cited U.S. Patents are hereby incorporated by reference.

This invention additionally covers derivatives of rapamycin in which one of the 31- or 42-hydroxyl groups has been convened to a carbamate, as described above, and the other of the 31- or 42-hydroxyl groups has been esterified with a moiety that it is not an allyl or propargylamino carbamate. Such other esters include acyl derivatives of rapamycin as described in U.S. Pat. No. 4,316,885, which is hereby incorporated by reference; fluorinated esters of rapamycin as described in U.S. Pat. No. 5,100,883, which is hereby incorporated by reference; amide esters of rapamycin as described in U.S. Pat. No. 5,118,677, which is hereby incorporated by reference; carbamates of rapamycin as described in U.S. Pat. No. 5,118,678, which is hereby incorporated by reference; aminoesters of rapamycin as described in U.S. Pat. No. 5,130,337, which is hereby incorporated by reference; ethers and acetals of rapamycin as described in U.S. Pat. No. 5,151,413, which is hereby incorporated by reference; aminoacyl esters of rapamycin as described in U.S. Pat. No. 4,650,803, which is hereby incorporated by reference; sulfonates and sulfamates of rapamycin as described in U.S. Pat. No. 5,117,203, which is hereby incorporated by reference; silyl ethers of rapamycin as described in U.S. Pat. No. 5,120,842, which is hereby incorporated by reference; and sulfonylcarbamates of rapamycin as described in U.S. Pat. No. 5,194,447, which is hereby incorporated by reference. Similarly, this invention covers compounds in which one hydroxyl of rapamycin has been converted to an allyl or a propargyl amino carbamate and the other hydroxyl is an inorganic ester of the hydroxyl group. These esters include phosphate, nitrate, sulfinate, sulfonate esters, and the like, and organic esters of these inorganic acids.

Immunosuppressive activity for representative compounds of this invention was evaluated in an in vitro standard pharmacological test procedure to measure lymphocyte proliferation (LAF) and an in vivo standard pharmacological test procedure. The in vivo pinch skin graft test procedure measures the immunosuppressive activity of the compound tested as well as the ability of the compound tested to inhibit or treat transplant rejection. The procedures used in these standard pharmacological test procedures are provided below.

The comitogen-induced thymocyte proliferation procedure (LAF) was used as an in vitro measure of the immunosuppressive effects of representative compounds. Briefly, cells from the thymus of normal BALB/c mice are cultured for 72 hours with PHA and IL-1 and pulsed with tritiated thymidine during the last six hours. Cells are cultured with and without various concentrations of rapamycin, cyclosporin A, or test compound. Cells are harvested and incorporated radioactivity is determined. Inhibition of lymphoproliferation is assessed as percent change in counts per minute from non-drug treated controls. For each compound evaluated, rapamycin was also evaluated for the purpose of comparison. An IC₅₀ was obtained for each test compound as well as for rapamycin. When evaluated as a comparator for the representative compounds of this invention, rapamycin had an IC₅₀ ranging from 0.56 and 2.8 nM. The results obtained for the representative compounds of this invention are provided as IC₅₀ s and are also expressed as a ratio compared with rapamycin. A positive ratio indicates immunosuppressive activity. A ratio greater than 1 indicates that the test compound inhibited thymocyte proliferation to a greater extent than rapamycin. Calculation of the ratio is shown below. ##EQU1##

Representative compounds of this invention were also evaluated in an in vivo test procedure designed to determine the survival time of pinch skin graft from male BALB/c donors transplanted to male C₃ H(H-2K) recipients. The method is adapted from Billingham R. E. and Medawar P. B., J. Exp. Biol. 28:385-402, (1951). Briefly, a pinch skin graft from the donor was grafted on the dorsum of the recipient as a allograft, and an isograft was used as control in the same region. The recipients were treated with either varying concentrations of test compounds intraperitoneally or orally. Rapamycin was used as a test control. Untreated recipients serve as rejection control. The graft was monitored daily and observations were recorded until the graft became dry and formed a blackened scab. This was considered as the rejection day. The mean graft survival time (number of days ±S.D.) of the drug treatment group was compared with the control group. The following Table shows the results that were obtained. Results are expressed as the mean survival time in days. Untreated (control) pinch skin grafts are usually rejected within 6-7 days. The results shown in Table 1 are based on a dose of 4 mg/kg of test compound. A survival time of 11.83±0.75 days was obtained for rapamycin at 4 mg/kg.

The following table summarizes the results obtained with representative compounds of this invention in these two standard test procedures.

                  TABLE 1                                                          ______________________________________                                         EVALUATION OF IMMUNOSUPPRESSIVE ACTIVITY                                                  LAF                                                                             IC.sub.50         Skin Graft                                       Compound    nM        ratio*  (days ± SD)**                                 ______________________________________                                         Example 2   0.77      1.2     11.5 ± 0.6                                    Example 3   1.4       0.64    10.5 ± 0.8                                    Example 4   0.24      2.3     11.67 ± 0.5                                   Example 5   0.9       0.9                                                      Example 6   3.5       0.8     11.2 ± 0.4                                    No Treatment                   7.00 ± 0.00                                  ______________________________________                                          *Vide supra for the calculation of the ratio.                                  **data obtained in Chremophor                                            

The results of these standard pharmacological test procedures demonstrate immunosuppressive activity both in vitro and in vivo for the compounds of this invention. Positive ratios in the LAF test procedures indicates suppression of T-cell proliferation, thereby demonstrating the immunosuppressive activity of the compounds of this invention. As transplanted pinch skin grafts are typically rejected within 6-7 days without the use of an immunosuppressive agent, the increased survival time of the skin graft when treated with the compounds of this invention further demonstrates their utility as immunosuppressive agents and as agents useful for treating and preventing transplantation rejection and graft vs. host disease.

Based on the results of these standard pharmacological test procedures, the compounds are useful in the treatment or inhibition of transplantation rejection such as kidney, heart, liver, lung, bone marrow, pancreas (islet cells), cornea, small bowel, and skin allografts, and heart valve xenografts; in the treatment or inhibition of graft vs. host disease; in the treatment or inhibition of autoimmune diseases such as lupus, rheumatoid arthritis, diabetes mellitus, myasthenia gravis, and multiple sclerosis; and diseases of inflammation such as psoriasis, dermatitis, eczema, seborrhea, inflammatory bowel disease, pulmonary inflammation (including asthma, chronic obstructive pulmonary disease, emphysema, acute respiratory distress syndrome, bronchitis, and the like), and eye uveitis.

Because of the activity profile obtained, the compounds of this invention also are considered to have antitumor, antifungal activities, and antiproliferative activities. The compounds of this invention therefore are also useful in treating solid tumors, adult T-cell leukemia/lymphoma, fungal infections, and hyperproliferative vascular diseases such as restenosis and atherosclerosis. When used for restenosis, it is preferred that the compounds of this invention are used to treat restenosis that occurs following an angioplasty procedure. When used for this purpose, the compounds of this invention can be administered prior to the procedure, during the procedure, subsequent to the procedure, or any combination of the above.

When administered for the treatment or inhibition of the above disease states, the compounds of this invention can be administered to a mammal orally, parenterally, intranasally, intrabronchially, transdermally, topically, intravaginally, or rectally.

It is contemplated that when the compounds of this invention are used as an immunosuppressive, antirejection, or antiinflammatory agent, they can be administered in conjunction with one or more other immunoregulatory agents. Such other immunoregulatory agents include, but are not limited to azathioprine, corticosteroids, such as prednisone and methylprednisolone, cyclophosphamide, rapamycin, cyclosporin A, FK-506, OKT-3, and ATG. By combining the compounds of this invention with such other drugs or agents for inducing immunosuppression or treating inflammatory conditions, lesser amounts of each of the agents are required to achieve the desired effect. The basis for such combination therapy was established by Stepkowski whose results showed that the use of a combination of rapamycin and cyclosporin A at subtherapeutic doses significantly prolonged heart allograft survival time. [Transplantation Proc. 23:507 (1991)].

The compounds of this invention can be formulated neat or with a pharmaceutical carrier to a mammal in need thereof. The pharmaceutical carrier may be solid or liquid. When formulated orally, it has been found that 0.01% Tween 80 in PHOSAL PG-50 provides an acceptable oral formulation.

A solid carder can include one or more substances which may also act as flavoring agents, lubricants, solubilizers, suspending agents, fillers, glidants, compression aids, binders or tablet-disintegrating agents; it can also be an encapsulating material. In powders, the carrier is a freely divided solid which is in admixture with the finely divided active ingredient. In tablets, the active ingredient is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain up to 99% of the active ingredient. Suitable solid carriers include, for example, calcium phosphate, magnesium stearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine, low melting waxes and ion exchange resins.

Liquid carriers are used in preparing solutions, suspensions, emulsions, syrups, elixirs and pressurized compositions. The active ingredient can be dissolved or suspended in a pharmaceutically acceptable liquid carder such as water, an organic solvent, a mixture of both or pharmaceutically acceptable oils or fats. The liquid carder can contain other suitable pharmaceutical additives such as solubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoring agents, suspending agents, thickening agents, colors, viscosity regulators, stabilizers or osmo-regulators. Suitable examples of liquid carriers for oral and parenteral administration include water (partially containing additives as above, e.g. cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols, e.g. glycols) and their derivatives, and oils (e.g. fractionated coconut oil and arachis oil). For parenteral administration, the carrier can also be an oily ester such as ethyl oleate and isopropyl myristate. Sterile liquid carriers are useful in sterile liquid form compositions for parenteral administration. The liquid carder for pressurized compositions can be halogenated hydrocarbon or other pharmaceutically acceptable propellant.

Liquid pharmaceutical compositions which are sterile solutions or suspensions can be utilized by, for example, intramuscular, intraperitoneal or subcutaneous injection. Sterile solutions can also be administered intravenously. The compound can also be administered orally either in liquid or solid composition form.

The compounds of this invention may be administered rectally in the form of a conventional suppository. For administration by intranasal or intrabronchial inhalation or insufflation, the compounds of this invention may be formulated into an aqueous or partially aqueous solution, which can then be utilized in the form of an aerosol. The compounds of this invention may also be administered transdermally through the use of a transdermal patch containing the active compound and a carrier that is inert to the active compound, is non toxic to the skin, and allows delivery of the agent for systemic absorption into the blood stream via the skin. The carder may take any number of forms such as creams and ointments, pastes, gels, and occlusive devices. The creams and ointments may be viscous liquid or semisolid emulsions of either the oil-in-water or water-in-oil type. Pastes comprised of absorptive powders dispersed in petroleum or hydrophilic petroleum containing the active ingredient may also be suitable. A variety of occlusive devices may be used to release the active ingredient into the blood stream such as a semipermiable membrane covering a reservoir containing the active ingredient with or without a carder, or a matrix containing the active ingredient. Other occlusive devices are known in the literature.

In addition, the compounds of this invention may be employed as a solution, cream, or lotion by formulation with pharmaceutically acceptable vehicles containing 0.1-5 percent, preferably 2%, of active compound which may be administered to a fungally affected area.

The dosage requirements vary with the particular compositions employed, the route of administration, the severity of the symptoms presented and the particular subject being treated. Based on the results obtained in the standard pharmacological test procedures, projected daily dosages of active compound would be 0.1 μg/kg-100 mg/kg, preferably between 0.001-25 mg/kg, and more preferably between 0.01-5 mg/kg. Treatment will generally be initiated with small dosages less than the optimum dose of the compound. Thereafter the dosage is increased until the optimum effect under the circumstances is reached; precise dosages for oral, parenteral, nasal, or intrabronchial administration will be determined by the administering physician based on experience with the individual subject treated. Preferably, the pharmaceutical composition is in unit dosage form, e.g. as tablets or capsules. In such form, the composition is sub-divided in unit dose containing appropriate quantities of the active ingredient; the unit dosage forms can be packaged compositions, for example, packeted powders, vials, ampoules, prefilled syringes or sachets containing liquids. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form.

The following examples illustrate the preparation of representative compounds of this invention.

EXAMPLE 1

42O-(4-Nitro-phenoxycarbonyl)rapamycin

To a solution of 5.15 g (5.633 mmol) of rapamycin in 40 ml of methylene chloride cooled to -78° C. with dry ice/acetone bath, was added 0.7 ml dry pyridine and 1.70 g (8.450 mmol) of p-nitrophenylchloroformate dissolved in 10 ml methylene chloride. The reaction mixture was allowed to warm to ambient and stirred overnight under nitrogen. The reaction mixture was concentrated in vacuo and partitioned between ether and water. The organic phase was washed with 0.1N HCl (3×), then with a saturated sodium chloride solution (2×), dried over magnesium sulfate, filtered and concentrated under vacuum to give a pale yellow solid. Purification by flash column chromatography (elution with 40% then 50% ethyl acetate/hexanes) gave 5.41 g (88% ) of the title compound as a pale yellow solid.

¹ H NMR (DMSO) d 8.3 and 7.5 (aromatic-H, 4H), 4.5 (42C-H, 1H).

MS (-) FAB m/z: 1078 (M⁻), 590 (Southern Fragment).

EXAMPLE 2

42O-(Benzyloxyaminocarbonyl)rapamycin

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves) a mixture of 42O-(4-nitro-phenoxycarbonyl)rapamycin (0.700 g, 0.648 mmole), O-benzylhydroxylamine hydrochloride (0.154 g, 0.965 mmole), DMAP (0.196 g, 1.607 mmole), and anhydrous CH₂ Cl₂ (14 ml) was stirred for 1 hour at 0° C., followed by overnight stirring at ambient temperature. The mixture was filtered, diluted with 200 ml of ethyl acetate and washed with water (2×100 ml), brine (1×100 ml), dried (MgSO₄), and evaporated to dryness. The crude product was preabsorbed on silica gel and purified by flash chromatography (silica gel Merck 60, step gradient from 20 to 45% ethyl acetate in hexane). The clean fractions were combined, evaporated, dried in vacuo to afford 0.309 g of title compound.

¹ H NMR (CDCl₃, 400 MHz): δ 1.63 (s, 3H, 6-CH₃), 1.73 (3H, 30-CH₃), 3.12 (s, 3H, 41-CH₃ O), 3.31 (s, 3H, 7-CH₃ O), 3.35 (s, 3H, 32-CH₃ O), 4.86 (d, 2H, NOCH₂, side chain at C-42), 4.60 (m, 1H, 42-CH), 7.23 (s, 1H, OCONH, side chain at C-42-), 7.32-7.39 (m, 5H, H arom.)

¹³ C NMR (CDCl₃, 400 MHz): δ 215.36, 208.18, 169.21, 166.75, 157.05, 140.13, 136.03, 135.55, 135.49, 133.62, 130.13, 129.54, 129.15, 128.58, 128.51, 126.57, 126.37, 98.47, 84.79, 84.33, 80.91, 80.85, 67.17, 59.28, 57.38, 55.91, 55.86, 51.26, 46.59, 44.20, 41.46, 40.60, 40.19, 38.93, 38.32, 35.91, 35.08, 33.74, 33.23, 32.93, 32.85, 31.22, 29.93, 27.24, 27.01, 25.27, 21.48, 20.65, 16.22, 16.04, 15.89, 13.71, 13.16, 10.14

MS (neg. ion FAB, m/z): 1062.0 [M]⁻, 590.0, 470.0

EXAMPLE 3

42O-(Allyloxyaminocarbonyl)rapamycin

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves) a mixture of 42O-(4-nitro-phenoxycarbonyl)rapamycin (0.700 g, 0.648 mmole), O-allylhydroxylamine hydrochloride (0.106 g, 0.968 mmole), DMAP (0.196 g, 1.607 mmole), and anhydrous CH₂ Cl₂ (14 ml) was stirred for 1 hour at 0° C., followed by overnight stirring at ambient temperature. The mixture was filtered, diluted with 200 ml of ethyl acetate and washed with water (2×100 ml), brine (1×100 ml), dried (MgSO4), and evaporated to dryness. The crude product was preabsorbed on silica gel and purified by flash chromatography (silica gel Merck 60, step gradient from 20 to 50% ethyl acetate in hexane). The clean fractions were combined, evaporated, dried in vacuo to afford 0.414 g (63.0% ) of title compound.

¹ H NMR (CDCl₃, 400 MHz): δ 1.63 (s, 3H, 6-CH₃), 1.73 (3H, 30-CH₃), 3.12 (s, 3H, 41-CH₃ O), 3.31 (s, 3H, 7-CH₃ O), 3.36 (s, 3H, 32-CH₃ O), 4.34 (d, 2H, NOCH₂, side chain at C-42), 4.60 (m, 1H, 42-CH), 5.25-5.30 (m, 2H, ═CH₂, side chain at C-42), 5.93 (m, 1H, ═CH, side chain at C-42), 7.26 (s, 1H, OCONH, side chain at C-42)

¹³ C NMR (CDCl.sub. 3, 400 MHz): δ 215.38, 208.23, 169.22, 166.75, 157.11, 140.14, 136.02, 135.62, 135.55, 133.62, 132.28, 130.13, 129.54, 126.57, 126.37, 120.29, 120.24, 98.46, 84.79, 84.74, 84.32, 80.89, 67.16, 59.29, 57.38, 55.91, 55.86, 51.25, 46.58, 44.20, 41.46, 40.58, 40.17, 38.93, 38.87, 38.30, 35.90, 35.07, 33.72, 33.20, 32.92, 32.85, 32.82, 31.20, 29.91, 27.23, 27.01, 25.27, 21.48, 20.64, 16.22, 16.04, 15.89, 15.83, 13.71, 13.68, 13.18, 13.16, 10.13

MS (neg. ion FAB, m/z): 1012.4 [M]⁻, 590.2, 420.2

EXAMPLE 4

42O-(Pyridine-4-ylmethoxy-aminocarbonyl)rapamycin

Step A. 2-(Pyridine-4-ylmethoxy)-isoindole-1,3-dione

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves), a mixture of N-hydroxyphthalimide (15.0g, 0.091 mole), 4-picolylchloride hydrochloride (15.0g, 0.091 mole), and triethylamine (27.7g, 0.273 mol) in 125 ml of anhydrous acetonitrile was refluxed for 2 hours. After stirring overnight at ambient temperature, TLC showed that the starting materials were practically consumed. Ethyl acetate (500 ml) was added, mixture stirred for 15 min and filtered. The solvent was evaporated and the residue dissolved in 1L of EtOAc. The filtrate was washed with water (2×500 ml), brine (1×500 ml), dried (MgSO₄), and evaporated to a smaller volume (100 ml). The mixture was cooled down to -18° C., precipitate filtered and recrystallized from EtOAc/hexane to afford 13.2g (56.8%) of title product.

¹ H NMR (DMSO-d₆, 400 MHz): δ 5.25 (s, 2H, CH₂) 7.52 (m, 2H, H arom), 7.86 (s, 4H, H arom, phthalimide), 8.61 (m, 2H, H arom)

MS (EI, m/z): 254 [M]⁺

Anal. Calcd. for C₁₄ H₁₀ N₂ O₃ : C, 66.14; H, 3.96; N, 11.02; Found: C, 65.84; H, 3.93; N, 10.87

Step B. Pyridine-4-ylmethyl-hydroxylamine dihydrochloride

A slurry of 2-(Pyridine-4-ylmethoxy)-isoindole-1,3-dione from Step A (7.0 g, 0.028 mol) in 70 ml of ethanol was treated with hydrazine hydrate (1.38 g, 0.028 mmol). The mixture was refluxed for 6 hours; the resulting precipitate was collected cold and washed with ethanol (2×25 ml). The filtrate was cooled to 0° C. and treated with HCl gas until pH 2-3 is reached. The precipitate that formed was collected and dried in vacuo to provide 4.0g of title product.

¹ H NMR (400 MHz, DMSO-d₆): δ 5.39 (s, 2H, CH₂), 7.97 (d, 1H, H arom), 7.99 (d, 1H, H arom), 8.90-8.92 (m, 2H, H arom).

MS (EI, m/z): 125 [M+H]⁺

Anal. Calcd. for C₆ H₁₀ C₁₂ N₂ O: C, 36.57; H, 5.11; N, 14.21; Found: C, 36.83; H 4.89; N, 13.89

Step C. 42O-(Pyridine-4-ylmethoxy-aminocarbonyl)rapamycin

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves), a mixture of rapamycin 42-carbonate (0.450 g, 0.417 mmole), amine dihydrochloride of Step B (0.163 g, 0.834 mmole), DMAP (0.153 g, 1.25 mmole), and anhydrous DMF (8 ml) is stirred for 1 hour at 0° C., followed by overnight at ambient temperature. The mixture is filtered, diluted with 200 ml of ethyl acetate and washed with water (2×100 ml), brine (1×100 ml), dried (MgSO₄), and evaporated to dryness. The crude product is preabsorbed on silica gel and purified by flash chromatography (silica gel Merck 60, step gradient from 50% ethyl acetate in hexane to pure ethyl acetate). The clean fractions are combined, evaporated, dried in vacuo to afford 0.348 g of title compound.

¹ H NMR (CDCl₃, 400 MHz): δ 1.65 (s, 3H, 6-CH₃), 1.73 and 1.75 (3H, 30-CH₃), 3.14 (s, 3H, 41-CH₃ O), 3.34 (s, 3H, 7-CH₃ O), 3.35 (s, 3H, 32-CH₃ O), 4.61 (m, 1H, 42-CH), 4.91 (S, 2H, CH₂, side chain at C-42), 7.49 (1H, OCONH, side chain at C-42), 7.32 (d, 2H, H arom), 8.61 (d, 2H, H arom)

¹³ C NMR (CDCl₃, 400 MHz): δ 215.18, 208.14, 169.24, 166.73, 157.19, 149.96, 144.69, 140.05, 136.02, 130.16, 135.68, 133.54, 130.16, 129.44, 126.50, 126.41, 122.86, 98.47, 84.74, 84.27, 80.85, 67.16, 59.24, 57.22, 55.86, 51.26, 46.57, 44.19, 41.49, 40.47, 40.18, 38.93, 38.33, 35.82, 35.08, 33.76, 33.18, 32.79, 31.21, 31.11, 29.86, 27.21, 27.00, 25.25, 21.47, 20.64, 16.20,16.13, 15.97, 15.85, 13.66, 13.20, 10.14

MS (neg. ion FAB, m/z): 1063.8 [M]⁻, 590.6, 471.5

EXAMPLE 5

42O-(Pyridine-2ylmethoxy-aminocarbonyl)rapamycin

Step A. 2-(Pyridin-2-ylmethoxy)-isoindole-1,3-dione

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves), a mixture of N-hydroxyphthalimide (10.0 g, 0.061 mole), 2-picolylchloride hydrochloride (10.0 g, 0.061 mole), and triethylamine (18.5g, 0.183 mol) in 100 ml of anhydrous acetonitrile was refluxed for 6 hours. After overnight stirring at ambient temperature, TLC showed that the starting materials were practically consumed. The solvent was evaporated and the residue dissolved in 200 ml of EtOAc. The solution was washed with 1N NaOH (100 ml), water (2×200 ml), brine (1×200 m ml) and dried (MgSO₄). After removal of the solvent, the crude product was recrystallized from EtOAc/hexane to afford 11.4g (73.6%) of title product.

¹ H NMR (DMSO-d₆, 400 MHz): δ 5.23 (s, 2H, CH₂), 7.38 (m, 1H, H arom), 7.68 (m, 1H, H arom), 7.85 (s, 4H, H arom, phthalimide), 7.87 (m, 1H, H arom), 8.51 (1H, CH═N--)

MS (EI, m/z): 254 [M]⁺

Step B. Pyridine-2-ylmethoxyamine dihydrochloride

A slurry of the 2-(pyridin-2-ylmethoxy)-isoindole-1,3-dione from Step A (5.0 g, 0.020 mol) in 50 ml of ethanol was treated with hydrazine hydrate (1.0 ml, 1.03 g, 0.020 mmol). The mixture was refluxed for 1 hour, the precipitate filtered cold, and washed with ethanol (2×25 ml). The filtrate was cooled to 0° C. and treated with HCl gas until pH 2-3 was reached. The precipitate was collected and dried in vacuo to provide 3.53g of title product.

¹ H NMR (400 MHz, DMSO-d₆): δ 5.31 (s, 1H, CH₂), 7.68 (m, 1H, H atom.), 7.75 (d, 1H, H arom.), 8.18 (m, 1H, H arom.), 8.73 (m, 1H, H arom.)

MS (pos. DCI, isobutane; m/z): 125 [M+H]⁺

Step C. 42O-(Pyridine-2-ylmethoxy-aminocarbonyl)rapamycin

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves) a mixture of 42O-(4-nitro-phenoxycarbonyl)rapamycin (0.400 g, 0.371 mmole), amine dihydrochloride of Step B (0.144 g, 0.741 mmole), DMAP (0.136 g, 1.11 mmole), and anhydrous DMF (10 ml) was stirred for 30 min. at 0° C., followed by overnight stirring at ambient temperature. The combined crude material from 2 reaction runs (for a total of 0.500g of 42O-(4-nitrophenoxycarbonyl)rapamycin) was filtered, diluted with 200 ml of ethyl acetate and washed with water (2×100 ml), brine (1×100 ml), dried (MgSO₄), and evaporated to dryness. The crude product was preabsorbed on silica gel and purified by flash chromatography (silica gel Merck 60, step gradient from 50% ethyl acetate in hexane to pure ethyl acetate). The clean fractions were combined, evaporated, dried in vacuo to yield 0.359 g of title product.

¹ H NMR (CDCl₃, 400 MHz): δ 1.59 (s, 3H, 6-CH₃), 1.69 (3H, 30-CH₃), 3.08 (s, 3H, 41-CH₃ O), 3.27 (s, 3H, 7-CH₃ O), 3.30 (s, 3H, 32-CH₃ O), 4.59 (m, 1H, 42-CH), 4.98 (s, 2H, OCH₂ C, side chain at C-42), 7.20 (m, 1H, H arom), 7.38 (m, 1H, H arom), 7.66 (m, 1H, H aromat.), 7.81 (s, 1H, OCONH, side chain at C-42), 8.54 (m, 1H, H arom)

¹³ C NMR (CDCl₃, 400 MHz): δ 215.28, 208.15, 169.20, 166.74, 156.11, 140.09, 136.70, 136.01, 135.59, 133.59, 130.13, 129.50, 126.53, 126.38, 123.01, 122.51, 98.46, 84.76, 84.30, 80.87, 78.63, 78.06, 67.15, 59.25, 57.39, 55.85, 51.24, 46.57, 44.19, 41.46, 40.59, 40.17, 38.90, 38.29, 35.90, 35.08, 33.74, 33.21, 32.82, 31.20, 29.90, 27.22, 27.01, 25.25, 21.47, 20.64, 16.21,16.01, 15.88, 13.68, 13.17, 10.13

MS (neg. ion FAB, m/z): 1063.4 [M]⁻, 590.3, 471.2

EXAMPLE 6

42O-(Prop-2-ynyloxy-aminocarbonyl)rapamycin

Step A. Prop-2-ynylhydroxylamine hydrochloride

A slurry of 2-(Prop-2-ynyloxy)-isoindole-1,3-dione (10.0 g, 0.050 mol) in 50 ml of anhydrous ether was treated with hydrazine hydrate (2.54 ml, 2.62 g, 52.2 mmol). The mixture was stirred for 1.5 hour at room temperature; a precipitate formed that was collected, and washed with ether (2×25 ml). The filtrate was cooled to 0° C. and HCl gas is bubbled until pH 2-3 was reached. The mixture was stirred for 10 hours at 0° C., the precipitate that formed was collected, and dried in vacuo at 35° C. to provide 3.68g of title product.

¹ H NMR (400 MHz, DMSO-d₆): δ 3.84 (t, 1H, CH), 4.75 (t, 2H, CH₂)

MS (EI, m/z): 71 [M]⁺

Anal. Calcd. for C₃ H₆ ClNO: C, 33.51; H, 5.62; N, 13.02; Found: C, 34.78; H 5.08; N, 13.14.

Step B. 42O-(Prop-2-ynyloxy-amino carbonyl)-rapamycin

Under anhydrous conditions (positive nitrogen pressure, presence of 3 Å molecular sieves) a mixture of 42O-(4-nitro-phenoxycarbonyl)rapamycin (0.500 g, 0.463 mmole), the product of Step A (0.149 g, 1.39 mmole), DMAP (0.226 g, 1.85 mmole), and anhydrous DMF (10 ml) was stirred for 2 hours and filtered. The filtrate was diluted with 200 ml of ethyl acetate, washed with water (4×100 ml), brine (1×100 ml), dried (MgSO₄), and evaporated to dryness. The crude product was preabsorbed on silica gel and purified by flash chromatography (silica gel Merck 60, step gradient from 25 to 30% ethyl acetate in hexane). The clean fractions were combined, evaporated, dried in vacuo to yield 0.320 g (68.3 % ) of desired product.

¹ H NMR (CDCl₃, 400 MHz): δ 1.655 (s, 3H, 6-CH₃), 1.751 (3H, 30-CH₃), 2.52 (t, 1H, C.tbd.CH , side chain at C-42), 3.14 (s, 3H, 41-CH₃ O), 3.33 (s, 3H, 7-CH₃ O), 3.38 (s, 3H, 32-CH₃ O), 4.51 (d, 2H, OCH₂ C.tbd.CH , side chain at C-42), 4.62 (m, 1H, 42-CH), 7.54 (1H, OCONH, side chain at C-42)

¹³ C NMR (CDCl₃, 400 MHz): δ 215.41, 208.22, 192.57, 169.25, 166.78, 156.81, 140.15, 136.04, 135.60, 133.63, 130.16, 129.55, 126.60, 126.40, 98.47, 86.41, 84.77, 84.33, 80.88, 80.82, 77.93, 67.16, 59.28, 57.38, 57.34, 55.85, 51.25, 46.58, 44.19, 41.46, 40.89, 40.84, 40.57, 40.17, 38.92, 38.29, 35.87, 35.08, 33.72, 33.19, 32.91, 32.82, 31.22, 31.16, 29.86, 27.22, 26.99, 25.25, 21.46, 20.62, 16.37,16.19, 16.14, 15.99, 15.87, 14.94, 13.67, 13.14, 10.27

MS (neg. ion FAB, m/z): 1010.6 [M]⁻, 590.4, 418.3 

What is claimed is:
 1. A method of treating transplantation rejection or graft vs. host disease in a mammal in need thereof, which comprises administering to said mammal an antirejection effective amount or a compound of the structure ##STR9## wherein R¹ and R² are each, independently, hydrogen, or --CONH--O--(CR³ R⁴)_(m) Z;R³ and R⁴ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, cycloalkyl of 3-8 carbon atoms, --CF₃, or F; Z is hydrogen, alkyl of 1-6 carbon atoms, --OR⁵, --SR⁵, --NR⁵ R⁶, --CN, --CF₃, --OAr, --Ar, or R⁷ ; R⁵ and R⁶ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, arylalkyl of 4-10 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthioalkyl of 2-12 carbon atoms, alkylaminoalkyl of 2-12 carbon atoms, dialkylaminoalkyl of 3-12 carbon atoms, cycloalkyl of 3-8 carbon atoms, or Ar; R⁷ is ##STR10## or --C.tbd.C--R¹¹ ; R⁸, R⁹, R¹⁰, and R¹¹ are each, independently, hydrogen, alkyl of 1-6 carbon atoms, halogen, or phenyl, wherein the phenyl group may be optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, trifluoroalkoxy of 2-7 carbon atoms, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H; Ar is an aryl radical that may be optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, hydroxy, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, trifluoroalkoxy of 2-7 carbon atoms, amino, dialkylamino of 1-6 carbon atoms per alkyl group, dialkylaminoalkyl of 3-12 carbon atoms, hydroxyalkyl of 1-6 carbon atoms, alkoxyalkyl of 2-12 carbon atoms, alkylthio of 1-6 carbon atoms, --SO₃ H, --PO₃ H, and --CO₂ H; and m=1-6; with the proviso that R¹ and R² are both not hydrogen, or a pharmaceutically acceptable salt thereof. 